2007 Fiscal Year Final Research Report Summary
International project to investigate the world-oldest biogenic graphite
| Project/Area Number |
17403011
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 海外学術 |
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| Research Field |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | Tohoku University |
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Principal Investigator |
KAKEGAWA Takeshi Tohoku University, Tohoku University, Graduate School of Science, Associate Professor (60250669)
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| Project Period (FY) |
2005 – 2007
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| Keywords | Early Earth / Early life / Graphite / Crust / Isua / Greenland / Steep Rock |
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| Research Abstract |
The main purpose of this study is to investigate the newly found outcrops in the Isua Supracrustal Belt in Greenland and accumulate more evidence for activities of the earliest life with collaborating with Prof. Rosing at Copenhagen University. The world-oldest rocks, 3.8 Ga, are distributing in this Isua Supracrustal Belt. We performed intensive geological surveys during summers of 2005, 2006 and 2007. Newly found rocks contain abundant graphite. Detailed geochemical data suggest that such graphite was biogenic in origin. In addition, detailed TEM observation indicates a unique texture in graphite, which suggests that graphite was not formed later processes, thus biogenic in origin.
In addition, we also found nano-sized graphite in magnetite crystals in banded iron formations; the first report from banded iron formations in Isua. This discovery further suggests that graphite were ubiquitous in the 3.8 Ga oceans.
We also performed geological surveys in the Steep Rock area in Canada, in order to compare the Isua's results to younger rocks. The oldest organic molecules indicating activities of oxygenic photosynthesis were found through the course of the present study. We also proposed that nano-sized metallic oxides incorporated the organic matter can be used as a new type of biomarker to indicate the activity of oxygenic photosynthesis.
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Research Products
(63 results)
